Critical factors for grain filling in low grain-ripening rice cultivars
Critical factors for grain filling in low grain-ripening rice cultivars
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DOI：
10.2134/agronj2005.0139
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发表时间：
2006-05
期刊：
影响因子：
2.1
通讯作者：
T. Kobata;Tomonori Nagano;Kumiko Ida
中科院分区：
文献类型：
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作者：
T. Kobata;Tomonori Nagano;Kumiko Ida
一些改良水稻（Oryza sativa L.）IRRI的新株型（NPT）系或日本籼粳品种等品种可以附加更大的小穗密度，因此具有更高的产量潜力（YP）;然而，籽粒成熟度低意味着它们较高的YP没有得到充分利用。我们的目标是澄清为什么他们的籽粒成熟度低于其他品种，以及是否低同化物供应的粮食或小穗库能力不足，限制在这些情况下的籽粒成熟。田间试验结果表明，IR 65564 -44-2-2（NPT）和Akenohoshi（籼×粳）品种的结实率和小穗充实率较低。当在灌浆期（GFP）将植株密度减半以提高植株干物质增加量时，Akenohoshi的PRG和F%增加，而IR 65564 -44-2-2和其他品种几乎没有变化。由于PRG或F%与PRG/YP之间的密切关系，对YP的同化物供应不足限制了大多数品种的PRG;然而，在IR 65564 -44-2-2中，增加PRG和F %并没有提高PRG和F%。在YP较高的品种中，IR 65564 -44-2-2的F%随积温的升高开始下降较早。当在早期GFP期间分离的穗在完全营养培养基中培养1周时，培养的Akenohoshi和IR 65564 -44-2-2中的F%显著大于田间条件下的F %。这些结果表明，劣质同化物供应是较低的籽粒成熟的Akenohoshi的主要原因，而在籽粒成熟的早期下降，可能是由于较高的小穗不受精，是在IR 65564 -44-2-2负责的因素。
Some improved rice (Oryza sativa L.) cultivars such as the new plant type (NPT) lines of IRRI or Japanese indica × japonica cultivars can attach a greater density of spikelets, and hence have higher yield potential (YP); however, low grain ripening means that their higher YP is not fully used. Our objective was to clarify why their grain ripening is lower than in other cultivars, and whether low assimilate supply to grains or insufficient sink capability of spikelets restricts grain ripening in these cases. IR65564-44-2-2 (NPT) and Akenohoshi (indica × japonica) cultivars yield lower percentages of ripened grain (PRG) and have lower spikelet filling percentages (F%) than other cultivars in field trials. When plant density was halved during the grain-filling period (GFP) to improve plant dry-matter increase (DMI), PRG and F% in Akenohoshi increased, but scarcely changed in IR65564-44-2-2 and other cultivars. Inferior assimilate supply to YP limited the PRG in most cultivars due to close relationships between PRG or F% and DMI/YP; however, in IR65564-44-2-2 increased DMI/YP did not improve PRG and F%. Among the higher YP cultivars, F% in IR65564-44-2-2 started to decrease earlier with accumulated temperature. When panicles detached during the early GFP were cultured in a complete nutrient medium for 1 wk, F% in cultured Akenohoshi and IR65564-44-2-2 was significantly greater than that under field conditions. These results suggest that inferior assimilate supply is the main cause of lower grain ripening in Akenohoshi, whereas the earlier decrease in grain ripening, probably due to higher spikelet nonfertilization, is the factor responsible in IR65564-44-2-2.